An environmental audit of the likely impact of offshore wind farms on wildlife has indicated that Britain's coastal waters have space for up to 7,000 more wind turbines than are already planned.

The 5,000 to 7,000 turbines recommended by the report, released as part of preparations for the third phase of offshore wind farm development around the country, would be enough to supply almost every home in Britain with electricity.

Ed Miliband, the Energy Secretary, expressed confidence over the prospects of offshore wind farms as the government-commissioned report into the environmental impact was launched.

"In terms of electricity, offshore wind power could potentially make the single biggest contribution to our 2020 renewable energy target so it's vital we maximise the UK's natural resources to help in the fight against climate change," he said. "This report provides a real advance in our understanding of the ecology and geology of the UK marine environment so we can continue to ensure that projects like wind farms are built in the most suitable places."

A 12 week consultation on the report has now started and the report will also be examined by the Crown Estate, which as owner of the seabed is drawing up plans for a third round of licensing offshore wind farms.

A BWEA spokesman said: "The government's view is that there are no obstacles in terms if impact on the environment or the wildlife. The potential impact will be greatly outweighed by the future benefits of these projects. On the one hand impacts will be minimal, on the other hand potential benefits to the country as a whole will be enormous, so it is really quite a clear situation."